1. Field of the Invention
The present invention relates to a composition for use in the treatment of heart failure of mammals which comprises an N.sup.6 -substituted-adenosine-3',5'-cyclic phosphate or its physiologically acceptable salt as an active ingredient and a pharmaceutically acceptable carrier, as well as to a method for treating heart failure of mammals which comprises administering said composition.
2. Description of the Prior Art
Adenosine-3',5'-cyclic phosphate (hereinafter referred to as "C-AMP") itself exhibits no myocardial contractility when administered to heart [J. Pharmacol. Exptl. Therap., Vol. 139, 269 (1963)]. However, it is known that N.sup.6,2'-O-dibutyryl C-AMP [Jpn. J. Pharmacol., 24, 499 (1974)] and 8-substituted-C-AMP [Chem. Pharm. Bull., 28, 1683 (1980)] which are derivatives of C-AMP have a mycocardial contractile effect.
The present inventors conducted many studies on the pharmacological activities of various C-AMP derivatives to find that N.sup.6 -substituted-C-AMP and its salts have a strong positive inotropic effect and are useful as a therapeutic agent for heart failure of mammals. Based on this finding, the present invention was accomplished.